The present invention relates to a device for supplying electrical energy to an ozonizer for frequencies from 400 Hz to several tens of kHz.
Presently known industrial ozonizers comprise two electrodes separated by a dielectric and a discharge space in which a dry gas containing oxygen circulates. If a voltage sufficiently high to reach the breakdown point of the gas is applied to the terminals of these electrodes, a corone discharge occurs between them. The brush discharge dissociates the oxygen in the discharge space and thus forms a gas containing a concentration of ozone which depends on the power applied and on the gas flow rate.
Two different types of supply devices for these ozonizers exist in the state of the art.
Supply devices comprise a frequency converter making it possible to increase the supply frequency of the ozonizer with respect to the frequency of the mains and to improve the production of ozone. These converters consist of inverters of parallel or series type, to which is connected either an L.C.-type resonant load or an uncompensated, forced-switching, non-resonant load which is much less expensive than the L.C. loads, but exhibits a deplorable power factor. An arrangement of a series-type inverter is described in French patent No. 39.770 (FR 1 544 857) entitled xe2x80x9cSystxc3xa8me d""alimentation xc3xa9lectrique pour ozoneurxe2x80x9d [Electrical supply system for ozonizer].
Another type of series inverter is described in French patent No. 69.17372 entitled xe2x80x9cPerfectionnement aux dispositifs d""alimentation à frxc3xa9quence moyenne d""un circuit rxc3xa9cepteur prxc3xa9sentant une impxc3xa9dance variablexe2x80x9d [Improvement to middle-frequency devices for supplying a receiver circuit exhibiting variable impedance].
On the one hand the improvement in the performance of ozonizers and more particularly their capacity to economically to produce ozone at high concentration is leading to ever more capacitive loads bringing about a large reduction in the power factor of the load as viewed from the power source. These conditions demand the use of load compensation so as to optimize the dimensioning of the power source.
On the other hand, the improvement in the performance of components that generate ozone is leading to the search for an increase in the power applied per unit area (power density), this making it necessary, for a given configuration (Manley""s formula), to increase the power density by increasing the frequency or increasing the voltage. The frequencies generally used for industrial ozonizers are currently less than 2000 Hz. Small ozonizers operate at a higher frequency by using supplies which cannot be applied economically to the design of industrial ozonizers.
In the devices described above, it is vital to employ a very particular technique for adjusting the assembly, especially for tuning the high-voltage transformer so as to obtain the best conditions of operation. It is also very important to master the technology of power switches, linked with more constraining switching due to the load. Moreover, these systems also have the disadvantage of needing starter means which complicate the operating sequences and raise the cost of the apparatus. This culminates in relatively complex devices of high cost price and unoptimized operation.
The purpose of the invention is to create a device making it possible to design, as inexpensively as possible, a supply for an industrial ozonizer that is stable in operation at frequencies lying between 400 Hz and high frequencies reaching as much as several tens of kHz.
To this end, the subject of the invention is a device for supplying electrical energy to an ozonizer, characterized in that it comprises a DC supply source, to the terminals of which are connected a dual series inverter bridge coupled to a resonant load composed of a high-voltage choke in series with the ozonizer.